1. Field of the Disclosure
The present disclosure relates to a method of fabricating a single-crystal silicon film and a method of fabricating a thin film transistor (TFT) adopting the same.
2. Description of the Related Art
Poly crystalline silicon (poly-Si) has higher carrier mobility than that of amorphous Si (a-Si), and thus, is utilized in a flat panel display device and in various electronic devices such as solar batteries. However, the carrier mobility and homogeneity of poly-Si are inferior to those of single-crystal Si.
Single-crystal Si is useful for a system on panel (SOP) structure, in which a system is formed on a display panel. The mobility of single-crystal Si is 300 cm2/Vs or higher. A high quality switching device used in a display device can be obtained from single-crystal Si having high mobility.
There are certain limitations in fabricating single-crystal Si, such as a limitation of processing temperature. When the single-crystal Si is fabricated, the processing temperature cannot rise over a certain temperature that can be endured by a material forming a substrate of the Si.
A method of fabricating a silicon-on-insulator (SOI) wafer using a so-called proprietary Smart-Cut technique includes an annealing process, the processing temperature of which rises up to 1000° C. The above method includes the operations of heat treating of a bare wafer having a predetermined thickness to form an oxide layer thereon, forming a boundary layer using hydrogen impurities by injecting hydrogen (H+) ions under the surface of the wafer, bonding the wafer to a separate substrate and separating the boundary layer to retain silicon of a predetermined thickness on the substrate, and annealing the silicon left on the substrate at the high temperature.
The temperature may rise over 900° C. in the thermal oxidation process, and over 1,100° C. in the annealing process. The high-temperature processes may degrade the characteristics of the substrate. Therefore, the material that can be selected to form the substrate is limited by the high temperature process, and the selected material undergoes thermal shock. Thus, the performance of the device formed using the silicon may be degraded.